The invention relates to a substrate comprising a glass sheet a main surface of which is provided with a synthetic resin layer. The invention also relates to a light-emitting device provided with such a substrate, and to a method of manufacturing such a substrate.
The English-language abstract of Japanese patent application JP-A-4-235527 describes a laminate of a relatively thick synthetic resin layer and a glass sheet. In JP-A-4-235527, a description is given of the application of the substrate in a light-emitting device for use in Liquid Crystal Displays. The known substrate has the drawback that it has a low flexibility, so that the range of applications is limited.
It is an object of the invention to provide a substrate which is flexible. To achieve this, the substrate in accordance with the invention is characterized in that the glass sheet has a thickness d which is smaller than or equal to 0.1 mm (d  less than 0.1 mm), the synthetic resin layer on the main surface of the sheet having a thickness dxe2x80x2 which is smaller than or equal to the thickness of the glass sheet (dxe2x80x2xe2x89xa6d). It has been found that such a sheet is flexible and that, in practice, bending with radii of curvature ranging from 3 to 4 cm is possible.
Also the processability, such as cutting and breaking of the substrate, has been improved because, during processing, the material cracks less easily at the edge. This effect is already obtained if a central part of the main surface is free of the synthetic resin layer.
A light-emitting device in accordance with the invention may be, for example, a poly-LED. Such a device is described in xe2x80x9cLEDsxe2x80x9d by R. Friend in Physics World, November 1992, pp. 42-46. Customary poly-LED displays comprise a substrate of a synthetic resin and have the favorable property that they are flexible. Such synthetic resin substrates, however, generally are permeable to oxygen and water. This limits the service life and the shelf life of the display. The flexible substrate in accordance with the invention obviates this drawback in that the glass sheet is non-permeable to oxygen and water.
Another example of a light-emitting device in accordance with the invention is a Plasma Addressed Liquid Crystal display. Such a device is described in U.S. Pat. No. 5,596,431.
The known display comprises a sandwich structure of two glass sheets. On a first glass sheet are deposited parallel, transparent column electrodes, customarily referred to as xe2x80x9cITOxe2x80x9d columns because indium-tin oxides are commonly used as the column material on which a layer of a color filter material is deposited.
A second glass sheet comprises parallel, closed plasma channels which correspond to rows of the display and cross all ITO columns, each channel being filled with a low-pressure ionizable gas, such as helium, neon or argon, and including cathode and anode structures which extend in the longitudinal direction of the channel to ionize the gas and generate a plasma. The channels are closed by a thin glass sheet. An electro-optical material, such as a liquid-crystal (LC) material, is situated between the first and the second glass sheet.
In such displays, the glass sheet is very thin (30-80 xcexcm) and cracks easily, thus causing rejects during the manufacture. Cracking usually starts at the edge. It has been found that the development of cracks can be reduced by using the substrate in accordance with the invention. Also the processability is improved.
The substrate in accordance with the invention can also be used in electrochromic devices.
A very favorable application of a light-emitting device is a light source in accordance with the invention, which is characterized in that it is embodied so as to be a sandwich of 2 substrates between which there is space which is filled with a suitable gas mixture and spacers.
The sub-claims define advantageous embodiments of the invention.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter, which constitute(s) a non-limitative example.